Yes I had previously done that calculation as well. The only thing I can think of is if you are (or maybe your employer is) already paying for a rack that is underutilized power-wise but has a little space left you can add a few of the miners.
I couldn't give a rats ass about nanometers or "sexy" miners (seriously you guys need to get out more). All I care about is price, delivery, reliability, hash rate, and power usage.
Obviously, I don't have to agree with you 100% (except for the part that I should get out more).. but you're right on the money with that fact that the ASIC doesn't need to look "pretty". To get the job done is the right attitude and it's not like we'd look like poster boys ourselves either.
Furthermore, it left me thinking about the 1.25U competitor.. If they consume between 1.2 - 1.35kW power, why bother with such a small factor (and risk with not being able to dissipate the heat effectively, hence more noise for fans spinning at max)? Yes, it is the coolest looking kid on the blockchain, but as most Data Centers can normally only facilitate up to between 8 to 12 kW of power per rack (including the equivalent in cooling), where lies the benefit in 1.25U when you can only fit 10 of those into a 42U rack maximum, leaving 70% of the rack unpopulated from a density point of view? Data Centers that could facilitate more power are few and far between.
In this sense, BITMAIN seems to be spot on with the sizing - but it does come down to the price and how well they can position themselves on the market. No doubt more competition is coming and the big names of the past are looking to regain their position.